It is a difficult and time consuming process to break roller chain into selective lengths. This is especially true of large chains, and chains having multiple spans.
Tools have been developed in the past for application of mechanical force to drive pins from chains. Such tools are typically called chain breakers, and are hand held devices with plier-like handles for application of mechanical force to drive the pins. Such tools have limited use, especially with multiple strand chains.
As a solution to the above problem, the present inventor developed a hydraulic chain breaker that made use of a hydraulic cylinder in a rigid frame for application of hydraulic force to break chains. While the hydraulic breaker was serviceable, several problems became evident with its use.
The hydraulic chain breaker included a rigid frame with a punch block and a sliding punch pin mountable within the frame in axial alignment with the hydraulic cylinder. Headed ends of the pin sliding punch was connected to the hydraulic cylinder by means of a threaded saddle with a punch receiving cleat welded thereon.
The cleat received the headed end of a sliding punch, releasably securing the punch to the cylinder. It was found that the punch would sometimes bind in the chain when driven axially to force a pin from the chain. It then became extremely difficult to separate the punch pin and block from the cylinder in order to clear the punch pin from the chain. Separation could occur only by unscrewing the saddle from the cylinder. This was found to be a slow and difficult process. A need thus arose for a better way to releasably secure the punch to the cylinder that would permit easy access for removal of the punch if binding should occur.
It was also found that the stroke length of the cylinder was such that the cleat could be forcefully driven against the punch block and crimped, binding the punch pin head in the cleat. A need was thus realized for an arrangement whereby the cleat could be protected against such damage.
A weakness was also found in the frame of the prior breaker, in the area of an opening formed in the frame for receiving the chain. This opening must permit free access for mounting and removal of chain at any point along the chain length. However, the forces applied, especially in multiple strand and large roller chains, could reach a point where the frame could bend. A need for reinforcement of the frame in this area was thus realized.
A need also arose for shields to assure user safety in the areas where the cylinder shaft connected to the punch, and over the chain receiving opening.
The above needs are filled by the present breaker which also provides further advantages that will become apparent from the following specification, drawings, and claims.